光在水中传输时的吸收和散射效应使得激光的水下传输特性变得复杂,尤其是后向散射会造成目标对比度降低,导致利用激光进行水下探测时面临挑战,而载波调制技术可以用来抑制水下激光雷达的后向散射。利用基于蒙特卡罗方法的计算机仿真技术建立余弦调制高斯脉冲激光水下传输模型,并讨论光载微波脉冲宽度、调制频率和调制深度等参数对探测结果的影响。结果表明:相比于传统脉冲激光雷达的仿真结果,载波调制相关检测技术可以有效提高水下目标对比度;脉冲宽度存在最佳值,调制频率对目标回波信号的信噪比和测距精度有影响,调制深度越大,目标回波信号的信噪比越高。

Due to the absorption and scattering effects of light in water, propagation characteristics of lasers underwater become complicated. In particular, the backscatter causes the target contrast to decrease, which makes the use of lasers in underwater detection face a great challenge. Carrier modulation technique can be used to suppress the backscatter for underwater lidar. Computer simulation based on Monte Carlo method is used to establish an underwater detection model for photons of Gaussian pulse lasers modulated by cosine signal. The effects of parameters such as pulse width, modulation frequency, and modulation depth on detection results are discussed. The results show that, compared with traditional pulse lidar simulation results, carrier modulation technique with correlation detection can effectively improve the underwater target contrast. The pulse width has the optimum range. The modulation frequency has effect on the signal-to-noise ratio and ranging accuracy of the target echo signal. The greater the modulation depth, the higher the signal-to-noise ratio of the target echo signal.